Fix glance configuration when using external ceph

When using external ceph, enable_ceph=no and glance_backend_ceph=yes,
glance.conf should enable rbd store.

Change-Id: Ia09cd57c829b00f28674cddf44fb55583e193d0f

ansible/roles/glance/defaults/main.yml

@@ -126,7 +126,7 @@ glance_backends:
   - name: http
     enabled: true
   - name: "rbd"
-    enabled: "{{ enable_ceph | bool and glance_backend_ceph | bool }}"
+    enabled: "{{ glance_backend_ceph | bool }}"
   - name: "vmware"
     enabled: "{{ glance_backend_vmware | bool }}"
   - name: cinder

ansible/roles/glance/templates/glance-api.conf.j2

@@ -56,7 +56,7 @@ filesystem_store_datadir = /var/lib/glance/images/
 stores = {{ glance_store_backends|map(attribute='name')|join(',') }}
 {% endif %}
 
-{% if enable_ceph | bool and glance_backend_ceph | bool %}
+{% if glance_backend_ceph | bool %}
 rbd_store_user = glance
 rbd_store_pool = {{ ceph_glance_pool_name }}
 rbd_store_chunk_size = 8